<template>
  <div class="component-upload-image">
    <el-upload
      :action="uploadImgUrl"
      list-type="picture-card"
      :on-success="handleUploadSuccess"
      :before-upload="handleBeforeUpload"
      :limit="limit"
      :on-error="handleUploadError"
      :on-exceed="handleExceed"
      name="file"
      :on-remove="handleRemove"
      :show-file-list="true"
      :headers="headers"
      :file-list="fileList"
      :on-preview="handlePictureCardPreview"
      :class="{hide: this.fileList.length >= this.limit}"
    >
      <i class="el-icon-plus"></i>
    </el-upload>

    <!-- 上传提示 -->
    <div class="el-upload__tip" slot="tip" v-if="showTip">
      请上传
      <template v-if="fileSize"> 大小不超过 <b style="color: #f56c6c">{{ fileSize }}MB</b> </template>
      <template v-if="fileType"> 格式为 <b style="color: #f56c6c">{{ fileType.join("/") }}</b> </template>
      的文件
    </div>

    <el-dialog
      :visible.sync="dialogVisible"
      title="预览"
      width="800"
      append-to-body
    >
      <img
        :src="dialogImageUrl"
        style="display: block; max-width: 100%; margin: 0 auto"
      />
    </el-dialog>
  </div>
</template>

<script>
  import { getToken } from "@/utils/auth";

  export default {
    props: {
      value: [String, Object, Array],
      // 图片数量限制
      limit: {
        type: Number,
        default: 1,
      },
      // 大小限制(MB)
      fileSize: {
        type: Number,
        default: 500,
      },
      // 文件类型, 例如['png', 'jpg', 'jpeg']
      fileType: {
        type: Array,
        default: () => ["mp4"],
      },
      // 是否显示提示
      isShowTip: {
        type: Boolean,
        default: true
      }
    },
    data() {
      return {
        dialogImageUrl: "",
        dialogVisible: false,
        hideUpload: false,
        baseUrl: process.env.VUE_APP_BASE_API,
        uploadImgUrl: process.env.VUE_APP_BASE_API + "/common/upload", // 上传的图片服务器地址
        headers: {
          Authorization: "Bearer " + getToken(),
        },
        fileList: []
      };
    },
    watch: {
      value: {
        handler(val) {
          if (val) {
            // 首先将值转为数组
            const list = Array.isArray(val) ? val : this.value.split(',');
            // 然后将数组转为对象数组
            this.fileList = list.map(item => {
              if (typeof item === "string") {
                if (item.indexOf(this.baseUrl) === -1) {
                  item = { name: this.baseUrl + item, url: this.baseUrl + item };
                } else {
                  item = { name: item, url: item };
                }
              }
              return item;
            });
          } else {
            this.fileList = [];
            return [];
          }
        },
        deep: true,
        immediate: true
      }
    },
    computed: {
      // 是否显示提示
      showTip() {
        return this.isShowTip && (this.fileType || this.fileSize);
      },
    },
    methods: {
      // 删除图片
      handleRemove(file, fileList) {
        const findex = this.fileList.map(f => f.name).indexOf(file.name);
        if(findex > -1) {
          this.fileList.splice(findex, 1);
          this.$emit("input", this.listToString(this.fileList));
        }
      },
      // 上传成功回调
      handleUploadSuccess(res) {
        this.fileList.push({ name: res.fileName, url: res.fileName });
        this.$emit("input", this.listToString(this.fileList));
        this.loading.close();
      },
      // 上传前loading加载
      handleBeforeUpload(file) {
        let isImg = false;
        if (this.fileType.length) {
          let fileExtension = "";
          if (file.name.lastIndexOf(".") > -1) {
            fileExtension = file.name.slice(file.name.lastIndexOf(".") + 1);
          }
          isImg = this.fileType.some(type => {
            if (file.type.indexOf(type) > -1) return true;
            if (fileExtension && fileExtension.indexOf(type) > -1) return true;
            return false;
          });
        } else {
          isImg = file.type.indexOf("image") > -1;
        }

        if (!isImg) {
          this.$message.error(
            `文件格式不正确, 请上传${this.fileType.join("/")}图片格式文件!`
          );
          return false;
        }
        if (this.fileSize) {
          const isLt = file.size / 1024 / 1024 < this.fileSize;
          if (!isLt) {
            this.$message.error(`上传头像图片大小不能超过 ${this.fileSize} MB!`);
            return false;
          }
        }
        this.loading = this.$loading({
          lock: true,
          text: "上传中",
          background: "rgba(0, 0, 0, 0.7)",
        });
      },
      // 文件个数超出
      handleExceed() {
        this.$message.error(`上传文件数量不能超过 ${this.limit} 个!`);
      },
      // 上传失败
      handleUploadError() {
        this.$message({
          type: "error",
          message: "上传失败",
        });
        this.loading.close();
      },
      // 预览
      handlePictureCardPreview(file) {
        this.findvideocover(file.url,file);
        this.dialogImageUrl = file.url;
        this.dialogVisible = true;
      },
      // 对象转成指定字符串分隔
      listToString(list, separator) {
        let strs = "";
        separator = separator || ",";
        for (let i in list) {
          strs += list[i].url.replace(this.baseUrl, "") + separator;
        }
        return strs != '' ? strs.substr(0, strs.length - 1) : '';
      },
      findvideocover(url,file) {
        // const  video = document.getElementById("myvideo"); // 获取视频对象
        const video = document.createElement("video") // 也可以自己创建video
        video.src=url // url地址 url跟 视频流是一样的

        // var canvas = document.getElementById('mycanvas') // 获取 canvas 对象
        var canvas = document.createElement('canvas') // 获取 canvas 对象
        const ctx = canvas.getContext('2d'); // 绘制2d
        video.crossOrigin = 'anonymous' // 解决跨域问题，也就是提示污染资源无法转换视频
        video.currentTime = 1 // 第一帧

        video.oncanplay = () => {
          console.log(video.clientWidth, video.clientHeight);
          canvas.width = video.clientWidth ? video.clientWidth : 320; // 获取视频宽度
          canvas.height = video.clientHeight ? video.clientHeight : 320; //获取视频高度
          // 利用canvas对象方法绘图
          ctx.drawImage(video, 0, 0, canvas.width,canvas.height)
          // 转换成base64形式
          this.videoFirstimgsrc = canvas.toDataURL ("image/png"); // 截取后的视频封面
          file.url = this.videoFirstimgsrc;
          // base64转成bolb文件
          const fileBolb = this.base64toFile(this.videoFirstimgsrc, this.getFileName(file))
          // 把首图上传生成云上地址
          this.getFirstPngUrl(fileBolb);
          video.remove();
          canvas.remove();
        }
      },
      base64toFile (baseUrl, filename = 'file') {
        let arr = baseUrl.split(',');
        let type = arr[0].match(/:(.*?);/)[1];   // 解锁图片类型
        let bytes = atob(arr[1]); // 解码base64
        let n = bytes.length
        let bufferArray = new Uint8Array(n);
        while (n--) {
          bufferArray[n] = bytes.charCodeAt(n);
        }
        return new File([bufferArray ],filename,{ type });

      },

      getFirstPngUrl(file){
        const fd = new FormData();
        fd.append('file',file);
        // this.$post为我自己封装的axios的post方法。可直接用axios的post方法
        this.$post('http://www.baidu.com', fd, { headers: {'Content-Type': 'multipart/form-data',  },}).then(res=>{
          this.videoFirstimgsrc = res.url;
          this.videoWriteFileList[0].url = res.url;
        })
      },

      getFileName(file){
        const type = file.raw.type.split("/")[1];
        let name = '';
        if(type){
          name = file.raw.name.substring(0, file.raw.name.indexOf(`.${type}`));
        }
        return `${name}.png`;
      }
    }
  };
</script>
<style scoped lang="scss">
  // .el-upload--picture-card 控制加号部分
  ::v-deep.hide .el-upload--picture-card {
    display: none;
  }
  // 去掉动画效果
  ::v-deep .el-list-enter-active,
  ::v-deep .el-list-leave-active {
    transition: all 0s;
  }

  ::v-deep .el-list-enter, .el-list-leave-active {
    opacity: 0;
    transform: translateY(0);
  }
</style>

